MapEnvelope should be a real envelope and the behaviour moved to MapOf

[victornoel]

In the same way we improved the cactoos API by making ListEnvelope, SetEnvelope and so on real envelopes with actual behaviour such as equals, toString, hashcode, etc, moved to the ListOf, SetOf, etc classes. I believe we should continue and do the same for MapEnvelope and MapOf.

The final objective is to have MapOf as the main entry point to build instances of Map in cactoos (based on a HashMap), and have Sticky and Solid removed.

The existing Grouped and Merged classes seems to be coherent with this desired design, so that's good.

[0crat]

@paulodamaso/z please, pay attention to this issue

[victornoel]

@0crat in

[victornoel]

@0crat assign @andreoss

[victornoel]

@andreoss I'm starting to assign manually because if not 0crat always assign latest issues and I would like to advance on those. I hope it's ok with you :) no rush anyway

[victornoel]

@andreoss thx :)

[0crat]

@sereshqua/z please review this job completed by @andreoss/z, as in §30; the job will be fully closed and all payments will be made when the quality review is completed

[sereshqua]

@0crat quality good